Schizophrenia, derived from the Greek for “severed mind,” refers to a mental disorder characterized by the fragmentation of mental functioning and a split between thinking and feeling. This entry discusses the definitions of the concept; the epidemiology and prevalence; and the course, causes, and functional assessment of schizophrenia. Then, this entry addresses rehabilitation, evidence-based practice, policy issues, and recovery.

Definitions of Schizophrenia

The origin of the concept of “schizophrenia” is usually attributed to the German psychiatrist Emil Kraepelin. Kraepelin first used the term dementia praecox, or “premature dementia,” to distinguish it from other psychotic illnesses. In the early 20th century, the Swiss psychiatrist, Eugen Bleuler, argued that the term dementia is misleading because dementia suggests an irreversible progressive brain disease. Bleuler stated that the most salient characteristic of the disorder is not its onset nor its course, but the particular nature of its expression in cognitive functioning. He proposed the term schizophrenia to suggest the fragmentation of mental functioning and a split between thinking and feeling. Bleuler also argued that there is extensive variability among individuals who had obtained this label, suggesting that there is a group of similar but distinct disorders. He made the new name plural, the schizophrenias. Although the term schizophrenia is used in contemporary diagnostic systems, the diagnostic criteria and subtypes found in the Diagnostic and Statistical Manual (DSM) are largely those of Kraepelin.

DSM diagnosis of schizophrenia requires the presence of at least two types of psychotic symptoms, including hallucinations, delusions, irregular affect, and confusion or disorientation. Delusions alone are sufficient if they are “bizarre” (i.e., they could not possibly be true, as when a person believes he or she is dead). Symptoms must be present for at least 6 months, unless suppressed by treatment, and must be accompanied by impairment in personal and social functioning. The diagnosis may be elaborated by the assignment of subtypes, based on the specific quality of the symptoms and the course of the disorder.

Historically, the concept of schizophrenia, and of psychiatric diagnosis in general, has been criticized as not being grounded in theory. Furthermore, in contrast with medical diagnoses, psychiatric diagnoses do not identify the cause of the illness. Typically, two opinions in the contemporary psychiatry and psychopathology communities emerge when describing schizophrenia. The first is a traditional view that schizophrenia is a unitary disease much like Kraepelin originally described. The second view is that schizophrenia is a generic category for a variety of specific disorders that have little in common other than periods of psychosis. This ambiguity is reflected in the existence of a related diagnosis, schizoaffective disorder, in which characteristics of schizophrenia co-occur with characteristics of affective disorders, primarily bipolar disorder or depression. Even when diagnosed rigorously with the criteria provided by the DSM, people receiving the diagnosis of schizophrenia comprise a very heterogeneous group with respect to age of onset, symptoms and other behavioral expressions of illness, degree of functional disability and other characteristics. There is no clinical picture that is unique to or always present in “schizophrenia.”

For these reasons, the term schizophrenia has limited utility in clinical treatment, social policy, or mental health administration. This has stimulated widespread use of the more inclusive term serious mental illness (SMI), which captures schizophrenia’s essential features, including a chronic course and severe functional disability.

Symptoms that are associated with schizophrenia can be separated into positive, negative, and disorganized symptoms. Sensory experiences, thoughts, and behaviors that are present but not typically found in people without the illness (e.g., hallucinations, delusions, and bizarre behavior) are called positive symptoms. Negative symptoms are so named because they refer to an absence or reduction of thoughts, feelings, and behaviors (e.g., reductions in communication, inability to feel pleasure (anhedonia), psychomotor retardation, apathy, and blunted affect). Negative symptoms are sometimes subdivided into primary and secondary symptoms. Primary negative symptoms are a direct expression of the disorder, while secondary symptoms are indirect consequences, such as depression consequent to loss of functioning, or side effects of medication (e.g., sedation). Finally, disorganized symptoms refer to a fragmentation of experience or behavior (e.g., disorientation, incoherent speech, purposeless motor activity). Although the most salient characteristics of schizophrenia tend to be positive or disorganized symptoms, negative symptoms account for a significant degree of morbidity associated with the disorder. Similarly, one of the most important insights about schizophrenia in recent decades has been that the disabilities associated with schizophrenia stem at least as much from the inability to perform activities of routine daily living as from symptoms.

Epidemiology and Prevalence of Schizophrenia

Schizophrenia occurs in 1% to 1.5% of the population. This rate is approximately the same across cultures. The meaning of this estimate is questionable, however, due to its reliance on the traditional diagnostic system. About 3% of the general population meet the more inclusive criteria for serious mental illness (SMI). The economic burden of SMI (e.g., cost of treatment, supportive social services, loss of productivity) is comparable to that of heart disease or cancer.

Course of Schizophrenia

The onset of schizophrenia typically occurs around adolescence. While the majority of individuals undergo a prodromal phase that involves a slow and gradual development of symptoms, onset can also be abrupt. Many factors can influence the onset and course of the disorder, including stress, genetics, environmental factors, gender, and culture. The course is usually episodic, meaning there are periods of more pronounced psychosis interspersed with periods of relatively intact functioning. However, people who meet diagnostic criteria are highly heterogeneous with respect to the frequency, duration, and severity of episodes. In some individuals, the episodes are so frequent, severe, and/or prolonged that the psychosis appears to be continuous.

Contrary to the common belief that persons afflicted with the disorder are doomed to interminable incapacity, many actually recover. Bleuler’s opposition to Kraepelin’s view of dementia praecox was based in part on his observation that approximately one third of people diagnosed with schizophrenia recover. Systematic research suggests that people recover at even higher rates, with up to two thirds recovering or significantly improving.

Causes of Schizophrenia

There is no single pathogen in the origins of schizophrenia. An array of factors interacts to produce the wide variability associated with the disorder. Environmental factors, especially stress, are thought to interact with a diversity of genetic, neuroanatomical, neurophysiological, neuropsychological, and behavioral vulnerabilities to produce the disorder. These interactions are understood to exert their influence over the span of childhood and adolescent development.

Genetic factors appear to play an important role; having a first-degree relative with schizophrenia increases a child’s risk of eventually being diagnosed with the disorder from 1.5% to approximately 10%. An identical twin with the diagnosis increases the risk for the other twin to about 50%. Pregnancy complications, abnormal fetal development, and/or birth complications are also related to an increased rate in developing schizophrenia. Theories about the mechanisms of genetic causes range from vulnerability to prenatal viral infection to abnormal distribution of specific neurotransmitter receptors.

Many studies have found structural abnormalities in the frontal lobes, temporal lobes, and basal ganglia. These studies support the theory that schizophrenia involves a widespread disturbance in cognitive coordination and its underlying neural basis. These findings may account for the wide range of cognitive deficits associated with schizophrenia. Neurodevelopmental studies reveal common neuromotor abnormalities in infancy and early childhood in individuals who develop schizophrenia in adolescence or adulthood.

Environmental factors such as poor nutrition, exposure to chemicals, viral disease, trauma, and psychosocial stressors may also result in an increased risk for the disorder. Possible links between environmental events and structural brain abnormalities include developmental neurodysplasia and Cortisol. Neurodysplasia is a relatively subtle disruption of brain development. The second trimester of gestation appears to be an especially vulnerable time for neurodysplasia to be induced through genetic abnormalities, viral infection, and toxic levels of cortisol or physical injury. Cortisol is a hormone secreted when a person is under stress. High levels of cortisol may produce neural cell death in brain areas associated with schizophrenia. Additionally, high cortisol levels in a pregnant woman may affect brain development in the fetus.

At the neurophysiological level, schizophrenia is generally understood as an episodic dysregulation of brain activity, possibly as a consequence of neuroanatomical abnormalities. The neurophysiological dysregulation is primarily mediated by the neurotransmitter dopamine. Pharmacological agents used to treat psychosis all affect the dopamine system, but there are intricate interactions between dopamine and other neurotransmitter systems, especially those mediated by serotonin. Newer pharmacological agents tend to have multiple actions across neurotransmitter systems.

Psychosocial influences can serve as environmental vulnerabilities that may exacerbate the disorder and further decrease functioning (e.g., family difficulties, poor interpersonal relationships, lack of social supports). Progression of the disorder can also be influenced by institutionalization and assumption of a “mental patient” social role. This highly dynamic accumulation of environmental and behavioral vulnerabilities, interacting with biological vulnerabilities, determines the lifelong course of the disorder.

Functional Assessment of Schizophrenia

Functional assessment is an individualized approach used in the assessment and treatment of individuals with SMI. Since the 1960s, functional assessment has become a very important clinical tool. Strengths and liabilities are evaluated on a continuum that includes neurobiological, cognitive, behavioral, and social-environmental levels of functioning. The most molecular levels of functioning include the impact of neurophysiological abnormalities. The intermediate levels include cognitive abilities (e.g., problem solving, self-monitoring, ability to make social inferences). The most molar levels of functioning extend to the person’s environment, and include family functioning, cultural attitudes about mental illness, and implications of public policy on service provision for individuals and families affected by SMI. The functional approach recognizes human beings as complex integrated systems, while affording a comprehensive picture of a client’s level of functioning, regardless of diagnosis. Most importantly, functional assessment informs case formulation, a comprehensive approach to understanding and treating the whole person.

Psychiatric Rehabilitation

Psychiatric rehabilitation is an integrated approach that combines functional assessment, psychosocial interventions, and biomedical treatment. Over the past three decades, psychiatric rehabilitation has gradually gained favor over “medical model” approaches limited to drug treatment and social support. Psychiatric rehabilitation typically combines multiple assessments and interventions (e.g., rehabilitation counseling, social skills training, wellness or illness management, cognitive therapy). The person undergoing treatment is a key collaborator in this process. Rehabilitation focuses on the reduction of disability while promoting more effective adaptation to the individual’s environment by using specific interventions to improve coping and behavioral abilities. This approach assumes that community adaptation consists of three factors: the characteristics of the individual, the community’s requirements for adequate functioning, and the supportiveness of the environment. Each of these three areas is a focus of assessment and treatment. Rehabilitation composed of comprehensive services combined with assessment and interventions that are individually tailored to clients’ needs has consistently resulted in a significant improvement in functioning. Psychiatric rehabilitation provides a promising approach to helping people in institutional settings achieve the abilities necessary to live in the community.

Evidence-Based Practice

Recently, the concept of evidence-based practice (EBP) has become a major focus of attention in health care, within and outside of mental health care. Treatment of schizophrenia is no exception. However, definitions of what constitutes “evidence-based practice” range from specific treatments tested in randomized controlled trials to broader combinations of empirical evidence, clinician experience, and systematic consideration of client values and desires. EBP principles can be straightforwardly applied to the specific modalities of psychiatric rehabilitation (e.g., pharmacotherapy, social skills training, and supported employment). It is less clear how evidence-based practice can be applied to the holistic, individualized approach of psychiatric rehabilitation. There is a pervasive tendency for mental health policy to adopt a “one size fits all” presumption about service needs despite the fact that people with SMI comprise a heterogeneous group with vastly diverse individual needs. Similarly, as recovery progresses, it is expected that different types of services will be optimal at different times throughout a person’s life. The near future will probably see extensive adaptation of evidence-based practice principles to the complexities of SMI and psychiatric rehabilitation.

Contemporary Policy Issues

Treatment and other services for SMI have undergone major structural changes over the past half century. Deinstitutionalization in the 1960s resulted in a change from an institution-based to a community-based mental health system. Unfortunately, many gaps and inconsistencies occurred in the community mental health system. Only the people who had a sufficient level of functioning and skill were able to remain in the community. Due to the unforeseen service gaps created by this shift, many people became “lost” within the community service system. People not engaged through traditional outpatient services were soon engaged by the criminal justice system, returned to the hospital, or became “revolving door” consumers of emergency services.

Movement toward a community system continues, and has brought into question the need for long-term inpatient services. Numerous states have closed or are in the process of closing state hospitals and developing community-based services. Unfortunately, some of these closures have been premature due to a lack of planning and supports needed to support the transition. Consequently, increases in homelessness, a disproportionate presence of people with SMI in the correctional system, and personal tragedies have occurred due to ill-considered risk factors. No state has completely eliminated its need for longer-term institutional services, although the number of people served in such settings has been dramatically reduced. The mission of the remaining services is changing, from providing permanent domicile to returning people to the community.

Recovery from Schizophrenia

The recovery movement is a social movement energized primarily by people with SMI, often known as “consumers” or “survivors” of mental health services. The movement has historical origins in the early 20th century, but has become most influential in national mental health policy over the past decade. Since the 1970s the recovery movement has been associated with psychiatric rehabilitation, to the degree that psychiatric rehabilitation has been characterized as “the technology of recovery.” No comprehensive definition of recovery exists, but all definitions advocate as a goal that the client will gain autonomy and independence. This contrasts with the traditional “medical model” goals of controlling symptoms and preventing relapse or hospitalization. The recovery concept provides a sense of hopefulness to people with SMI, with the idea that their diagnosis is not a terminal condition but rather one of possibility. It holds that people are more than their diagnosis, and counters the stigmatization that they are somehow the cause of their disabilities. The concept emphasizes that people with SMI must have a voice in their treatment and rehabilitation, and a sense of responsibility, instead of being passive recipients of services. The recovery movement gained a national forum in the United States in the 1999 Surgeon General’s Report on Mental Health, and more recently in the report of the 2003 President’s New Freedom Commission on Mental Health.

The report of the president’s commission calls for a national effort to strengthen the evidence base for rehabilitation and recovery methods, and to accelerate their dissemination. However, all aspects of research and treatment development have been vigorously criticized as lacking sufficient client participation. As with psychiatric rehabilitation research in general, the research that supports recovery would benefit from more systematic inclusion of clients’ perceptions of and experiences in actual treatment and other services.


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